Air bag for side air bag device

ABSTRACT

An air bag (11) for a side air bag device capable of reducing the size and weight of the device (M1) while retaining a tension line (L--L) when expanded is mounted on the peripheral edge of a door opening (W) at the inside of a compartment, and is formed into a generally rectangular bag shape for covering the door opening when expanded, while being equipped with a gas inlet (19) for introducing an expanding gas. The air bag is provided with joints (22) jointing an inner side wall (12) and an outer side wall (13) partially so as to form a tension line L--L when expanded. The individual joints (22) are juxtaposed in plurality along the tension line so as to cross the tension line, and are arranged generally at vertically middle portions so as to form one expansion chamber (18) having upper and lower spaces (18a and 18b) for the expanding gas to flow therethrough.

TECHNICAL FIELD

The present invention relates to an air bag for a side air bag device,which is mounted on the peripheral edge of a door opening inside of thecompartment of the body of a vehicle, and which is formed into agenerally rectangular bag shape for covering, such that, when opened,the door opening to protect the head of a passenger.

BACKGROUND ART

A side air bag device M0 of this kind in the prior art is constructed,as shown in FIG. 38, to include an air bag 1 mounted on the peripheraledge of a door opening W inside of the compartment of the body of avehicle, and an inflator 7 for discharging an expanding gas to inflatethe air bag 1.

The air bag 1 is composed of a plurality of expansion chambers to beexpanded into bags, uninflatable flat walls 4, 4 arranged at the frontand rear sides of the vehicle in the expansion chamber 2, and a pipeinsert 5 into which a pipe 6 for feeding the expanding gas from theinflator 7 is to be inserted.

The expansion chamber 2 is partitioned by joints 3 which are formed bystitching the inner side wall and the outer side wall of the air bag 1generally vertically from their respective upper to lower edges.

When this air bag 1 is to be inflated, the expanding gas is fed from theinflator 7 via the pipe 6 and through its not-shown through-holes toinflate the individual expansion chambers 2.

As these expansion chambers 2 are inflated, there is established atension along a line L--L which extends from the lower side to theobliquely upper side of the peripheral edge of the door opening W of theair bag 1, so that the air bag 1 can restrain the head of a passengerreliably by the tension line L--L, even when the air bag 1 is impactedby the passenger's head.

Here, the air bag 1 is mounted on the generally L-shaped portion or theperipheral edge of the door opening W. Unless the tension is establishedon the tension line L--L at the time of expansion, the air bag 1 willmerely move but fail to restrain the passenger's head properly even whenit is impacted by the head.

In the air bag 1 of the prior art, however, the expanding gas is fed tothe expansion chambers 2 which are partitioned in plurality, and theexpanding gas from the inflator 7 is fed via the long pipe 6sequentially into the individual expansion chambers 2. Since the pipe 6is inserted into the air bag 1, the air bag 1 is mounted in a bulkystate within the vehicle to enlarge the size of the side air bag deviceM0.

In the air bag 1 of the prior art, on the other hand, the expanding gasis fed to the expansion chambers 2 which are partitioned in plurality bythe joints 3. The expanding gas from the inflator 7 is fed via the longpipe 6 sequentially into the individual expansion chambers 2 so that thepressure-loss of the expanding gas is high. Unless the inflator 7 has ahigh output, the time period for completing the expansion of the air bag1 until the tension is exhibited on the tension line L--L is prolonged.

Moreover, the air bag 1 of the prior art is folded along the pipe insert5 on the peripheral edge of the opening W. The individual joints 3, asformed by stitching the inner side wall and the outer side wall to formthe plural expansion chambers 2, are formed in the folding directionperpendicular to the pipe insert 5. However, the stitching threadsforming the individual joints 3 overlap one another when the air bag 1is folded, and the joints 3 per se forming the expansion chambers 2 arenumerous, so that the air bag 1 cannot be folded compactly, which makesit difficult to retain sufficient space for the bag itself.

The present invention has been conceived to solve the above-specifiedproblems, and has as its object to provide an air bag for a side air bagdevice, which can reduce the size and weight of the device whileretaining the tension line at the time of expansion.

Another object of the invention is to provide an air bag for a side airbag device, which can suppress the pressure loss of the expanding gasand employ an inflator of a low output.

Still another object of the invention is to provide an air bag for aside air bag device, which can be folded compactly.

DISCLOSURE OF THE INVENTION

According to the invention, there is provided an air bag for a side airbag device adapted for mounting on the peripheral edge of a door openinginside of the compartment of a vehicular body,

which has a generally rectangular bag shape having a gas inlet in thelower side of the door opening peripheral edge for introducing anexpanding gas so as to cover the door opening when expanded, and

in which a tensing joint partially jointing an inner side wall and anouter side wall is arranged to form a tension line for establishing atension from the lower side to an obliquely upper side of the dooropening peripheral edge at the time of expansion,

characterized in that a plurality of the tensing joints are sojuxtaposed along the direction of the tension line as to cross thetension line; and

in that the individual tensing joints are arranged generally at verticalmiddle portions so as to form one expansion chamber having upper andlower spaces for the expanding gas to flow therethrough.

With this construction, when the air bag is to be expanded, theexpanding gas smoothly flows from the gas inlet through the upper andlower spaces of the individual joints to the portions between thejoints. In other words, the expanding gas can be smoothly fed withoutseparately inserting the pipe into the air bag so that the size andweight of the device can be reduced as a result of the elimination ofthe pipe.

On the other hand, the expanding gas flows through the upper and lowerspaces of the air bag so that the air bag can be expanded in a shorttime-period.

At the completion of the inflation (that is, at the completion of theexpansion), the tension line is formed so that the passenger's head canbe smoothly restrained.

At the completion of the inflation, moreover, a longitudinal expansionis formed in the lower portion of the air bag by the lower space so thatthe air bag can be further prevented from bending to enhance itsperformance in restraining the passenger.

In connection with the air bag according to the invention, moreover, theindividual tensing joints are desirably shaped to have curved bulgesbulging toward the gas inlet.

With this construction, the expanding gas is smoothly separatedvertically to flow to the portions separate from the gas inlet, even ifthe expansion gas impinges upon the joints, so that the pressure loss ofthe expanding gas can be suppressed to make it possible to employ theinflator of a low output.

In the air bag thus constructed, moreover, the individual tensing jointsmay have such recesses at the side opposed to the gas inlet so as to berecessed toward the gas inlet.

With this construction, as compared with the construction having norecess, the inner side wall and the outer side wall between theadjoining joints are individually pulled vertically so that therespective tensions in the juxtaposing direction of the joints, i.e.,the respective tension of the tension line, can be increased to enhancethe restraining performance of the air bag.

In connection with the air bag of the invention, on the other hand, thejoint arranged at the peripheral edge for forming the expansion chamber,and the individual joints for establishing the tension, may be formed bystitching the inner side wall and the outer side wall.

With this construction, when the air bag is to be expanded, the tensioncan be dispersed to act on the expansion chamber-forming joint and theindividual tensing joints, thereby to improve the respective strengthsof the joint portions.

Still moreover, the joint arranged at the peripheral edge for formingthe expansion chamber, and the individual joints for establishing thetension, are desirably formed by stitching the inner side wall and theouter side wall on condition that interposing a sheet material having anelasticity between the inner side wall and the outer side wall.

With this construction, the seams are sealed with the sheet material sothat the leakage of the expanding gas at the time of inflating the airbag can be suppressed to improve the retention of the internal pressureof the air bag being inflated.

Still moreover, the individual tensing joints are desirably formed bystitching the inner side wall and the outer side wall into a closedloop.

With this construction, as compared with the case of linear stitching,the stress concentration resulting from the tension acting upon theinner side wall and the outer side wall at the time of expansion can besuppressed to act on the stitched end portions of the joints, thereby toimprove the respective tensile strengths of the individual joints.

Still moreover, the joint arranged at the peripheral edge for formingthe expansion chamber, and the individual joints for establishing thetension, may be formed by adhering the inner side wall and the outerside wall together.

With this construction, as compared with the case in which the jointsare formed by stitchig them together with stitching thread, the absenceof any seam suppresses the leakage of the expanding gas at the time ofinflating the air bag, so that there is improved retention of theinternal pressure of the air bag being inflated.

Moreover, a front side fixed point of the air bag is set under a frontpillar, whereas a rear side fixed point of the air bag is set in a roofside rail near a quarter pillar.

With this construction, the air bag is expanded entirely over thelongitudinally wide range of the compartment, so that it can restrainthe head of a passenger reliably, even with any changes in thelongitudinal position of the seat or in the seated position of thepassenger.

Still moreover, in connection with the air bag of the invention, the airbag may be so arranged that its expansion area can include, whenexpanded, a portion of a center pillar so as to be supported by thecenter pillar when expanded.

With this construction, when the completely expanded air bag is impactedby the passenger's head, the air bag is jointed to and supported by notonly the peripheral edge of the door opening, but also the centerpillar, so that it can becomes more difficult to bend. This results inan enhancement of performance in terms of restraining the passenger.

Moreover, the portion to be supported by the center pillar at the timeof expansion may be expanded such that it is thicker than the remainingordinary expansion thickness.

With this construction, the cushioning effect of the air bag can beenhanced so as to restrain the passenger, even if it the air baginterferes with the center pillar. As compared with the case in whichthe portion to be supported by the center pillar is as thick as theremaining ordinary expansion thickness, the cushioning effect can beretained even if the initial internal pressure in the air bag islowered. Thereby, the output of the inflator can be lowered, and the airbag sealing method can be simplified, in order to reduce the size of theside air bag device.

When the portion of the air bag being expanded to be supported by thecenter pillar is set to be expanded thicker than the remaining ordinaryexpansion thickness, the expansion portion to be supported by the centerpillar at the time of expansion is so desirably formed that the gapbetween the adjoining joints is set larger than that of the adjoiningjoints in the remaining ordinary expansion area. With this construction,the expansion portion to be supported by the center pillar can be easilymade thicker than the remaining ordinary expansions thickness.

In connection with the air bag according to the invention, moreover, afront side fixed point is set under a front pillar, whereas a rear sidefixed point is set under a quarter pillar.

With this construction, the air bag, when expanded, is arranged at theside of not only the front seat but also the back seat, so that it canrestrain respective heads of the passengers seated not only in the frontseat but also in the back seat.

In connection with the air bag according to the invention, moreover, afront side fixed point is set under a front pillar. As compared with thecase in which the front side fixed point is fixed on the front pillar,the air bag can be expanded over a wide range to retrain the passengerover this wide range.

In connection with the air bag according to the invention, on the otherhand, a strap for jointing the inner side wall and the outer side wallto each other may be arranged between the joints at the side of the gasinlet and the gas inlet.

With this construction, even if the expanding gas flows from the gasinlet so as to establish a high tension at the inner side wall and theouter side wall at the gas inlet side, the tension can be obstructed bythe strap in order to lower the tension acting on the gas inlet side ofthe joints for establishing the tension line at the time of expansion.In short, the joints at the inlet side of the expanding gas can beprotected by the strap.

Moreover, the strap is desirably arranged to have its width directiongenerally at a right angle with respect to the inflow direction of theexpanding gas from the gas inlet.

With this construction, the expanding gas is directly impacted thestraps, and the joints at the gas inlet side can be indirectly impactedby the gas with reduced expansion force so that these joints can bebetter protected.

According to the invention, moreover, there is provided another air bagfor a side air bag device adapted to be mounted at the peripheral edgeof a door opening inside of the compartment of a vehicular body,

which other air bag has a generally rectangular bag shape having a gasinlet in the lower side of the door opening peripheral edge forintroducing an expanding gas so as to cover the door opening whenexpanded,

in which a tensing joint partially jointing an inner side wall and anouter side wall is arranged to form a tension line for establishing atension from the lower side to an obliquely upper side of the dooropening peripheral edge at the time of expansion, and

which is folded and accommodated in the door opening peripheral edge;

and is characterized: in that a plurality of the tensing joints arejuxtaposed along the direction of the tension line so as to cross thetension line;

in that the individual tensing joints are arranged generally at verticalmiddle portions so as to form one expansion chamber having upper andlower spaces for the expanding gas to flow therethrough; and

in that the air bag is folded and accommodated in a bellows shape withits folded overlapping faces being generally at a right angle withrespect to the door inner face.

In the air bag thus constructed, there is only one expansion chamber atthe time of expansion so that the projecting side joint, as folded whenaccommodated to project at the time of expansion, of the expansionchamber forming joints arranged on the peripheral edge for forming theexpansion chamber can be reduced in size. As a result, the air bag canhave reduced bulkiness after being completely folded, even if it isfolded so as to overlap the stitching thread or adhesive to be formed atthe projecting side joint. On the other hand, the tensing joints aredisposed generally at the vertically middle portions in the expansionchamber so that they are short in vertical height. This arrangement cancontribute to not only reduced in bulkiness of the folded air bag, butalso increased thinness of the folded air bag, even if the stitchingthread or adhesive for forming the tensing joints is over lapped.

As a result, the air bag thus constructed can be folded compactly. Sincethe air bag is folded and accommodated in a bellows shape with itsfolded overlapping faces being generally at a right angle with respectto the door inner face, the air bag can be quickly expanded along thedoor inner face.

In connection with the air bag, still moreover, the expansion chamber ofthe air bag may be manufactured by folding one cloth material and byjointing the peripheral edges of the cloth material excepting thecreases thereof such that the creases of the cloth material at the timeof forming the expansion chamber are arranged at the portions which areto be folded into the belows shape at the accommodation time.

With this construction, the projecting side joint of the expansionchamber forming joints to be arranged on the peripheral edge can befurther reduced, as a result, the air bag can be folded more compactly.

Moreover, of the expansion chamber forming joints arranged in theperipheral edge for forming the expansion chamber, the projecting sidejoint, as folded when accommodated but protruding when expanded, isdesirably arranged to be cross folded in the overlapping direction.

With this construction, the stitching thread or adhesion for forming theprojecting side joint can be displaced when the air bag is folded. As aresult, the air bag can be folded more compactly, and with reducedbulkiness after the completion of the folding operation.

Still moreover, the air bag is formed, when expanded, into aparallelogram bag shape, having two sides of an upper side with mountingmembers to be mounted on the peripheral edge of the opening inside ofthe compartment, and an oblique side leading at an obtuse angleobliquely downward from the upper side, and

the air bag is folded and accommodated so as to have creases in parallelwith the upper side and to overlap the upper side at a right angle.

With this construction, the air bag is folded from the upper sidesequentially with the crest and valley creases while holding themounting members of the upper side such that the creases are madestraight. As a result, the air bag can be easily folded by a simpleoperation. Here, the mounting members of the oblique side may be pulledout after the folding operation, and the air bag can be easily mountedon the peripheral edge of the opening because it is not inflated so asto have no tension line, in order that it can be easily deflected.

On the other hand, the air bag is accommodated within a case so as to befastened together with the body so that the air bag can be preventedfrom collapsing or being displaced out of position when assembled.

Moreover, the air bag is wrapped, when accommodated, in a folded stateso that it can be even more prevented from collapsing, and so that theair bag can be protected from any foreign substance when folded.Moreover, the air bag can be folded more compactly if wrapped whileunder a vacuum state. And by wrapping, the front pillar can also be madethinner be to improve the front view, and the roof side rail can be madethinner to widen the compartment.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a front elevation taken from the inside of a vehicularcompartment, and shows a side air bar device employing an air bagaccording to a first embodiment of the invention;

FIG. 2 is an enlarged section showing an essential portion taken alongline II--II of FIG. 1;

FIG. 3 is an enlarged section showing an essential portion taken alongline III--III of FIG. 1;

FIG. 4 is a view showing the side air bag device, when in an activatedstate, as employing the air bag of the embodiment;

FIG. 5 is a front elevation showing the air bag of the embodiment wheninflated;

FIG. 6 is an enlarged section taken along line VI--VI of FIG. 5;

FIG. 7 is an enlarged section taken along line VII--VII of FIG. 5;

FIG. 8 is an enlarged section taken along line VIII--VIII of FIG. 5;

FIG. 9 is a top plan view showing a cloth member for manufacturing theair bag of the embodiment;

FIG. 10 is a front elevation showing a modification of the air bag wheninflated;

FIG. 11 is a front elevation showing another modification of the air bagwhen inflated;

FIG. 12 is a front elevation showing still another modification of theair bag when inflated;

FIG. 13 is a partially enlarged front elevation showing a modificationof a tensing joint;

FIG. 14 is a partially enlarged front elevation showing anothermodification of a tensing joint;

FIG. 15 is a partially enlarged front elevation showing still anothermodification of a tensing joint;

FIG. 16 is a partially enlarged front elevation showing still anothermodification of a tensing joint;

FIG. 17 is a section corresponding to FIG. 6, but shows a modificationof joint means;

FIG. 18 is a section corresponding to FIG. 6, but shows anothermodification of joint means;

FIG. 19 is a section corresponding to FIG. 7, but shows the samemodification of joint means;

FIG. 20 is a section corresponding to FIG. 8, but shows the samemodification of joint means;

FIG. 21 presents diagrams for explaining a process for folding the airbag of the first embodiment;

FIG. 22 is a perspective view showing the body of a folding jig to beused in the process for folding the air bag of the same embodiment;

FIG. 23 is a perspective view showing a modification of the folding jig;

FIG. 24 is a front elevation showing another modification of the air bagwhen inflated;

FIG. 25 is a partially enlarged section showing a portion XXV--XXV ofFIG. 24;

FIG. 26 is a partially enlarged section showing a portion XXVI--XXVI ofFIG. 24;

FIG. 27 is a front elevation showing still another modification of theair bag when inflated;

FIG. 28 is a front elevation taken from the inside of a vehicularcompartment and shows a side air bar device, when in an activated state,as employing an air bag according to a second embodiment;

FIG. 29 is a diagram showing the side air bag device employing the airbag of the same embodiment;

FIG. 30 is a transverse section taken along line XXX--XXX of FIG. 28 andshows the air bag when inflated;

FIG. 31 is a partially enlarged section taken along line XXXI--XXXI ofFIG. 29;

FIG. 32 is a perspective view showing the air bag of the same embodimentwhen accommodated in a case;

FIG. 33 is a partially enlarged section taken along line XXXIII--XXXIIIof FIG. 29;

FIG. 34 is a section showing a modification of the case;

FIG. 35 is a perspective view showing the folded air bag when wrapped;

FIG. 36 is a front elevation showing still another modification of theair bag when inflated;

FIG. 37 is a front elevation showing still another modification of theair bag when inflated; and

FIG. 38 is a diagram showing an air bag of the prior art.

PREFERRED EMBODIMENTS OF THE INVENTION

An air bag 11 of a first embodiment is applied to a side air bag deviceM1 to be arranged from a front pillar FP of the peripheral edge of anopening W of a window inside of a vehicular compartment to the rear sideof a roof side rail RR, as shown in FIGS. 1 and 4. The side air bagdevice M1 is constructed to include: the air bag 11 folded andaccommodated in the generally L-shaped spatial portion from the frontpillar FP to the rear portion of the roof side rail RR; and an inflator24 for feeding an inflating gas to the air bag 11.

The air bag 11 is constructed, as shown in FIGS. 4 to 8, to include aninner side wall 12, an outer side wall 13 and a cylindrical gas inlet 19positioned at a lower position for introducing the inflating gas, andsuch that it takes a generally plate-like parallelogram bag shape wheninflated, which is comprised of an upper side 14, an oblique side 15leading obliquely downward at an obtuse angle from the upper side 14, alower side 16 leading from the oblique side 15 and confronting the upperside 14 generally in parallel, and a rear side 17 joining the rear endsof the upper side 14 and the lower side 16.

Moreover, the air bag 11 of the first embodiment is made of a generallyarrow-feather shaped cloth member 9 having a crease 9a at the lower side16 forming the lower edge of the inner side wall 12 and the outer sidewall 13, as shown in FIGS. 5 and 9. The air bag 11 is formed into a bagshape by folding the cloth member 9 along the center crease 9a, and bystitching the cloth material 9 along a predetermined peripheral edgewith joint means 10 such as a stitching thread 10a of polyester or thelike, so as to form a joint 20 for forming one expansion chamber 18. Thecloth material 9 is made of woven fabric of polyamide or polyester andhas flexibility. The stitching is performed using chain stitching or thelock stitching method.

Here, the joint means may be exemplified, by, in addition to thestitching thread 10a, employing an adhesive 10c such as a thermosetadhesive or hot melt adhesive of silicone, urethane or epoxy type, or byapplying the adhesive to the predetermined peripheral edge to joint theapplied portions into the bag shape, as in an air bag 111 shown in FIGS.18 to 20. As in an air bag 161 shown in FIG. 17, moreover, the innerside wall 12 and the outer side wall 13 may be stitched with thestitching thread l0a by sandwiching an elastic sheet member 10b made ofan adhesive layer of silicone tape or butyl rubber tape in between.

The expansion chamber forming joint 20 is comprised of a mounting sidejoint 20a extending from the upper side 14 to the oblique side 15including the gas inlet 19, and a projecting side joint 20b located atthe rear side 17 and accommodated in a folded state to project at thetime of inflation. At the upper side 14 and the oblique side 15 of themounting side joint 20a, respectively, there are formed a predeterminednumber of mounting members 14a and 15a having mounting holes 14b and15b. On the other hand, the rear side 17 of the projecting side joint20b is folded, when accommodated, together with the lower side 16, andis projected when inflated.

Here, at the rear side 17 of the air bag 11, there is formed anintegrating joint 21 at which the inner side wall 12 and the outer sidewall 13 are linearly jointed by the joint means 10. The integratingjoint 21 is provided, as shown in FIGS. 5 and 8, not to form theexpansion chamber 18 but to integrate the inner side wall 12 and theouter side wall 13 at their rear edges so as to prevent the air bag 11from fluttering when inflated.

Therefore, the peripheral edge of the expansion chamber 18 of the firstembodiment is defined by the crease 9a of the cloth material 9 or thelower side 16, the projecting side joint 20b at the rear edge apart fromthe gas inlet 19, and the mounting side joint 20a in front of theprojecting side joint 20b at the upper edge.

When the mounting side joint 20a is made, the gas inlet 19 is arrangedon the extension of the lower side 16. Since the cloth material 9 hasflexibility, however, the gas inlet 19 can be arranged on the extensionof the oblique side 15, when it is mounted on the peripheral edge of theopening W, by bending it easily.

When the joints 20 and 21 are to be made by folding the cloth material 9along the crease 9a, moreover, later-described tensing joints 22 arealso made to form the expansion chamber 18. The mounting holes 14b and15b of the individual mounting members 14 and 15 may be formed after themounting side joint 20a is made.

Moreover, the tensing joints 22 for forming a tension line L--L in theair bag 11 being inflated are provided by the stitching thread 10a, asshown in FIGS. 4 to 7, with bulges 22a bulging toward the gas inlet 19and recesses 22b at the side apart from the gas inlet 19, and are madeby jointing the inner side wall 12 and the outer side wall 13. In thecase of the embodiment, the four joints 22 are so arranged injuxtaposition along the tension line L--L at a vertical middle portionin the expansion chamber 18 as to form spaces 18a and 18b for passingthe inflating gas vertically within the air bag 11. Moreover, theindividual joints 22 of the embodiment are arranged across the tensionline L--L, and are stitched into a loop closing the inner side wall 12and the outer side wall 13. Here, the individual joints 22 may be doublystitched with the stitching thread 10a, as in an air bag 211 shown inFIG. 10, so as to increase their stitched strength.

The air bag 11 is accommodated, as shown in FIGS. 2 and 3, by folding itso as to form repeated crests and valleys sequentially with respect tothe peripheral edge of the opening W, and is covered at the side of thefront pillar FP with a garnish 33, and is covered at the side of theroof side rail RR with a roof interior member 35. Here, the overlappingfaces S of the air bag 11 are folded generally at a right angle withrespect to a door inner face DI.

The garnish 33 is comprised, as shown in FIGS. 1 and 2, of a mountingroot 33a, a base 33b and a surface 33c made of a synthetic resin such asan ABS resin or polypropylene, and is further comprised of a doorportion 33d which is arranged with an integral hinge 33e so that it ispushed and opened by the air bag 11 at the time the air bag 11 isinflated. The garnish 33 is fastened on a body 31 by means of clips 27or bolts. Here, these clips 27 or the like act to fasten the air bag 11onto the body 31 by inserting them together with a later-describedmounting belt 29 into the predetermined mounting holes 15b of the airbag 11.

The roof interior member 35 is comprised, as shown in FIGS. 1 and 3, ofa mounting root 35a, a base 35b and a surface 35c made of a syntheticresin such as urethane or polypropylene, and is fastened on the body 31by clips 27 or bolts such that its leading end 35b is retained on a doortrim 36 jointed to the body 31. When the air bag 11 is inflated,moreover, the leading end 35d is pushed by the air bag 11 out ofengagement with the door trim 36.

The mounting belt 29 for wrapping the folded air bag 11 is provided witha portion 29a which is made so thin as to be broken when the air bag 11is inflated, and is fastened together with the air bag 11 by the clips27 or bolts for fastening the air bag 11 to the body 31. Here, the airbag 11, as shown in FIGS. 2 and 3, is actually folded into a bellowsshape having more creases C, like the air bag 11 shown in FIG. 5.

At the front end of the air bag 11, on the other hand, the cylindricalgas inlet 19 is disposed over the inflator 24, and the cylindrical gasinlet 19 is mounted on the body 31 while being pushed onto the outercircumference of the inflator 24 by a mounting bracket 25 mounted on thebody 31.

The inflator 24 is constructed to include a generally cylindrical body24a having at its upper end a gas exit 24b for discharging the inflatinggas, and a not-shown cylindrical diffuser made of a sheet metal andcovering the circumference of the gas exit 24b. The inflator 24 ismounted on the body 31 by fitting the gas inlet 19 of the air bag 11around the diffuser, and by using the mounting bracket 25 for pushingthe gas inlet 19 onto the outer circumference of the diffuser. Here, themounting side joint 20a around the gas inlet 19 is folded around thediffuser.

Moreover, in a folding direction (i.e., an overlapping direction) Z forfolding the air bag 11 into the bellows shape, the air bag 11 is foldedtoward the upper side 14 at a right angle by forming the creases C inparallel with the upper side 14, as shown in FIG. 5. In the case of theembodiment, the air bag 11 is folded by employing a folding jig 40, asshown in FIGS. 21 and 22. This folding jig 40 is comprised of a body 41and a predetermined number of folding plate 45 having a width slightlysmaller than the folding width B of air bags 11. The body 41 isconstructed by arranging a vertical wall 43 on the upper face of a baseplate 42, and by arranging a holding wall 44 at such a position inparallel with the vertical wall 43 as is generally spaced by the foldingwidth B (as shown in FIG. 5).

In a process for folding the air bag 11 by employing the folding jig 40,as shown at A in FIG. 21, the expansion chamber 18 is arranged at theside of the vertical wall 43, and the root portion of the mountingmember 14a of the upper side 14 is arranged under the expansion chamber18. Then, the holding wall 44 is moved down so as to hold the rootportion of each mounting member 14a.

After this, as shown at B in FIG. 21, the outer side wall 13 of theexpansion chamber 18 is held from the inner side wall 12 between thevertical wall 43 and the holding wall 44 by the folding plate 45 so asto abut against the base plate 42.

Then, the air bag 11 is folded to form a crest, as shown at C in FIG.21, and the second folding plate 45 is arranged on the outer side wall13 to fold the air bag 11 to form a valley. From now on, the foldingplates 45 are sequentially inserted to repeat the crest and valleyfolds, as shown at D in FIG. 21.

After this, when the air bag 11 is folded to the vicinity of the lowerside 16, all the folding plates 45 are removed, as shown at E in FIG.21. As shown at F in FIG. 21, moreover, the holding wall 44 may be movedup to remove the folded air bag 11 from the holding jig 40. Here, thefolding jig 40 should not be limited to plate shapes, but may also beexemplified by the comb-shaped vertical walls 43 and holding walls 44,as shown in FIG. 23.

After the air bag 11 is thus folded up, the mounting member 15a, if itis folded during folding, may be pulled out. Then, the mounting members14a and 15a of the air bag 11 may be locally wrapped with the mountingbelts 29, and the inflator 24 may be assembled with the gas inlet 19 byemploying the mounting bracket 25. Then, the mounting belts 29 and themounting bracket 25 may be mounted together with the garnish 33 and theroof interior member 35 on the body 31 by employing the clips 27 or thelike thereby to mount the air bag device M1 on the vehicle.

Here, the air bag 11 can be easily mounted on the peripheral edge of theopening W, because it is not inflated such as not to form a tension lineL--L.

Into the mounting holes 14b at the rear end of the air bag 11, on theother hand, there are inserted bolts 38 without employing the mountingbelts 29, so that the air bag 11 is mounted at its rear end on the body31.

When the inflating gas is discharged from the gas exit 24b of theinflator 24 after the air bag device M1 is mounted, the air bag 11breaks the portions 29a of the individual mounting belts 29 to push andopen the door portion 33d of the garnish 33, and the leading end 35d ofthe roof interior member 35, so that the air bag 11 expands to close theopening W, as shown in FIG. 4.

In the air bag 11 of the first embodiment, the individual tensing joints22 are arranged generally at the vertically middle portions, andequipped over and under these middle portions with the spaces 18a and18b for guiding the expanding gas so as to integrate the inflatedexpansion chambers 18 into one single entity. Without providing any pipefor guiding the expanding gas, therefore, this gas smoothly flowsthrough the upper and lower spaces 18a and 18b into the portions betweenthe joints 22. Thus, the complete lack of need for any pipe enables areduction in the size and weight of the device M1 accordingly.

Moreover, the air bag 11 can be inflated (or expanded) for a short timebecause the inflating gas flows through the upper and lower spaces 18aand 18b of the air bag 11.

It is natural that at the completion of the inflation (or at the end ofthe expansion), the portions between the joints 22 are inflated to formthe tension line L--L to smoothly restrain the head of a passenger.

At the completion of the inflation, moreover, an inflated portion islongitudinally formed under the air bag 11 by the lower space 18b sothat the air bag 11 can be further prevented from bending in order toenhance the restraint on the passenger.

In the air bag 11 of the first embodiment, moreover, the tensingindividual joints at the time of expansion are equipped with the curvedbulges 22a to bulge toward the gas inlet 19, and are juxtaposedlongitudinally vis-a-vis the vehicle at its vertically middle portions.

Specifically, the individual joints 22 are not extended to the upperedge or to the lower edge of the air bag 11 so that the inflating gassmoothly flows over and under the joints 22 to the portions separatefrom the gas inlet 19. Moreover, the individual joints 22 are providedwith the curved bulges 22a bulging toward the gas inlet 19 so that theinflating gas is vertically separated to smoothly flow to the portionsseparate from the gas inlet 19, even if the air bag impinges upon thejoint portions 22. As a result, the pressure loss of the inflating gascan be suppressed so as to employ the inflator 24 of a low output.

In the air bag 11 of the first embodiment, moreover, there are formed inthe individual joints 22 at the opposite sides of the gas inlet 19 therecesses 22b which are recessed toward the gas inlet 19. Unlike joints272 having only bulges 272a, as shown in FIGS. 13 to 16, the inner sidewall 12 and the outer side wall 13 between the adjoining joints 22 arevertically pulled to increase the tension in the juxtaposition directionof the joints 22; i.e., the tension of the tension line L--L, so thatthe restraint of the air bag 11 can be enhanced. These effects can beachieved even for an air bag 311 which is stitched in a curved line withthe stitching thread 10a to juxtapose joints 322 having bulges 322a andrecesses 322b, as shown in FIG. 11. Even an air bag 261 having thejoints 272, as shown in FIGS. 13 to 16, can suppress the pressure lossof the expanding gas because it has the bulges 272a bulging toward thegas inlet 19.

These tensing joints 22, 272 and 322 should not be limited to the shownones but may be enabled to form the tension line L--L by forming theminto short linear or arcuate shapes, and by jointing the inner side wall12 and the outer side wall 13 in the expansion chamber 18 with the jointmeans 10 such as the stitching thread 10a. Here, when the individualtensing joints 22, 272 and 322 are made linear, they may be so formed asdesired to intersect the folding direction Z of the air bag 11, in orderthat the stitching thread l0a or the like may not be overlapped, whileallowing these joints to be folded compactly.

In the air bag 11 of the first embodiment, on the other hand, the innerside wall 12 and the outer side wall 13 are stitched at each joint 22into a closed loop. Unlike the linearly stitched air bag 311 of FIG. 11,therefore, the stress concentration, as might otherwise act upon theinner side wall 12 and the outer side wall 13 at the time of expansion,can be suppressed at the end portions of the joints 22 thereby toimprove the respective tensile strengths of the individual joints 22.This effect per se can naturally be achieved from the joints 272, asshown in FIGS. 13 to 16. It is especially desired that the joints 272 bestitched into curved loops having no sharp corner.

Here, the first embodiment is exemplified by the joints 22 which appearas crescent shaped in the front view. However, similar effects to thoseof the air bag 11 of the first embodiment can be achieved, also, from anair bag 361 having the joints 372 which are formed by stitching thebulges 372a and the recesses 372b into loop shapes with the stitchingthread 10a, as shown in FIG. 12.

In the air bag 11 of the first embodiment, on the other hand, both thejoint 20 for forming the expansion chamber of the peripheral edge andthe joints 22, as arranged in the middle portions of the air bag 11 forestablishing tension, are formed by stitching the inner side wall 12 andthe outer side wall 13 with the stitching thread 10a. As a result, thetension that occurs at the time of expansion can be dispersed betweenthe expansion chamber forming joint 20 and the individual tensing joints22, in order to enhance the strengths of the joints 20 and 22.

As in the air bag 161 shown in FIG. 17, the joints 20 and 22 for formingthe expansion chamber and establishing the tension are formed bystitching the inner side wall 12 and the outer side wall 13 with thestitching thread l0a of polyester, while sandwiching in between theflexible sheet member 10b having an elasticity and made of a siliconetape, a butyl rubber tape or an elastic adhesive layer. In addition tothe actions and effects thus far described, the seams can be sealed withthe sheet member 10b to suppress the leakage of the expanding gas at thetime of expansion of the air bag 161, thereby to increase the force formaintaining the internal pressure of the air bag 161 being inflated.

As in the air bag 111 shown in FIGS. 18 to 20, the expansion chamberforming and tensing joints 20 and 22 are formed by adhering the innerside wall 12 and the outer side wall 13 with the adhesive 10c. Becauseof the absence of the seams, the leakage of the expanding gas at thetime of expanding the air bag 111 can be more restrained than in thecase where the joints 20 and 22 are only stitched with the stitchingthread 10a, 10a; the result is an increase in the force for maintainingthe internal pressure of the air bag 111 being inflated. Here, similaractions and effects could be achieved, too, even if the joints 20 and 22are formed not by employing the adhesive 10c but by heating the innerside wall 12 and the outer side wall 13 to adhere them by fusion.

From the standpoint of protecting the tensing joints 22, on the otherhand, the air bag may be constructed as indicated at 411 in FIGS. 24 to26. In this air bag 411, a strap 100 is arranged between the joint 22Fat the side of the gas inlet 19 and the gas inlet 19 for jointing theinner side wall 12 and the outer side wall 13 to each other. The strap100 is made of a band of woven fabric of polyamide and polyester, and isstitched at its two end portions 100a and 100b to the inner peripheriesof the inner side wall 12 and the outer side wall 13 with the stitchingthread 10a, so that its width direction Y is generally at a right anglewith respect to a gas inflow direction I of the expanding gas comingfrom the gas inlet 19.

Even if the expanding gas flows from the gas inlet 19 into the air bag411 so that a high tension acts on the inner side wall 12 and the outerside wall 13 at the side of the gas inlet 19, the tension can be offsetby the strap 100 to reduce the tension which will act on the joint 22Fat the side of the gas inlet 19 in the joints 22 for establishing thetension line L--L at the time of expansion. In other words, the joint22F at the inflow side of the expanding gas can be protected by thestrap 100.

Here, this strap 100 may be so arranged that its width direction Y begenerally in parallel with the inflow direction I. However, if, asshown, the width direction Y is generally at a right angle with respectto the inflow direction I of the expanding gas coming from the gas inlet19, the expanding gas, which might otherwise directly impinge upon thejoint 22F, can be reduced in amount in order to better protect joint 22Fat the side of the gas inlet 19.

On the other hand, the length of the strap 100 can be suitably setwithin a range that leads to cause no slackness at the time of expandingthe air bag 411, if the strap 100 can be made to protect the joint 22Fat the side of the gas inlet 19. Especially, the length of the strap 100is desirably set so as make the strap 100 play a role in regulating thethickness of the expanded air bag 411 to a predetermined value. In thismodification, the arrangement of the strap 100 should not be limited toone location of the air bag 411 of the embodiment, but may be made at aplurality of locations so as to joint the inner side wall 12 and theouter side wall 13.

Moreover, the air bag 11 of the first embodiment is constructed suchthat neither the portion up to the integrating joint 21 at the back ofthe projecting side joint 20b nor the entirety of the air bag 11 isexpanded. This construction makes it possible to shorten the time perioduntil the completion of the expansion of the air bag 11, as well as toemploy an inflator having a low output.

On the other hand, the air bag 11 of the first embodiment is providedwith one expansion chamber 18 to be expanded such that the projectingside joints 20b, as folded when accommodated and projected whenexpanded, and located in the expansion chamber forming joints 20 to bearranged on the peripheral edge for forming the expansion chamber 18,can be reduced in size. Even if there is an overlap of the joint means10 such as the stitching thread 10a for forming the projecting sidejoint 20b at the folding time, the air bag 11 can be kept from becomingbulky after the end of its folding operation. Since the tensing joints22 are disposed generally at the vertical middle portions in theexpansion chamber 18 and given small vertical lengths, a contributioncan moreover be made to the reduction in size of the folded air bag 11as folded, while still keeping down its bulkiness, even if the stitchingthread 10a or the adhesive 10c for forming the tensing joints 22 overlapwhen folded.

As a result, the air bag 11 of the first embodiment can be foldedcompactly. Since the folded overlapping faces S are folded andaccommodated in the bellows shape generally at a right angle withrespect to the door inner face DI, the air bag 11 can moreover bequickly expanded along the door inner face DI.

Moreover, in the air bag 11 of the first embodiment, the creases 9a ofthe cloth material 9 at the time of manufacturing the expansion chamber18 are arranged at the portions to be folded at the folding time, andthe creases of the peripheral edge (including the creases 9a of thecloth material 9, the projecting side joint 20b at the rear sideseparate from the gas inlet 19, and the mounting side joint 20a in frontof the projecting side joint 20b at the upper edge) for forming theexpansion chamber 18. As a result, the projecting side joint 20b can befurther reduced in order to fold the air bag 11 more compactly.Especially in the embodiment, the creases 9a are arranged at the loweredge or the longer portion of the peripheral edge of the expansionchamber 18 so that the folding can be made more compact.

Unless this advantage is to be considered, the air bag 11 may be formedby jointing the two sheets of cloth material for the inner side wall 12and the outer side wall 13 by a stitching or adhering means.

In the air bag 11 of the first embodiment, on the other hand, of theexpansion chamber forming joint 20 to be arranged on the peripheral edgefor forming the expansion chamber 18, the projecting side joint 20b isso linearly arranged as to intersect the folding direction, i.e., in thefolded overlapping direction Z. As a result, the joint means such as thestitching thread 10a for forming the projecting side joint 20b isdisplaced to overlap even when the air bag 11 is folded, so that thebulkiness can be suppressed after the end of the folding operation.

In the first embodiment, the integrating joint 21 is also arranged tointersect the folding direction Z, and the stitching thread 10a or thelike can be displaced to overlap at the time of folding to preventbulkiness.

In the first embodiment, still moreover, the projecting side joint 20bis arranged at a position far away rearward from the tensing joint 22Bat the rear side so that the projecting side joint 20b and each tensingjoint 22 do not overlap, even in the folding direction Z. As a result,the overlap can be absolutely eliminated between the joint means 10,such as the stitching thread 10a for forming the projecting side joint20b, and the joint means 10, such as the stitching thread 10a forforming the tensing joints 22, thereby to make the folding more compact.

In the first embodiment, moreover, the folding direction Z of the airbag 11 is generally at a right angle with respect to the tension lineL--L so that the accuracy of the direction towards which the air bag 11is to project can be improved at the time of expansion, while alsomaking a contribution to the shortening of the time period until thecompletion of expansion. Here, the folding direction Z may be orientedto intersect the tension line L--L at a right angle by arranging thecreases C along the tension line L--L, as in an air bag 461 shown inFIG. 27.

Still moreover, the air bag 11 of the first embodiment is folded towardthe upper side 14 at a right angle with respect to the upper side 14 byforming the creases C in parallel with the upper side 14. If the air bag11 is folded sequentially with the creases C of crests and valleys fromthe side of the upper side while holding the mounting members 14a of theupper side 14, its folding operation is facilitated with the straightcreases C. Here, the mounting members 15a at the side of the obliqueside 15 may be pulled out after the folding operation. The air bag 11 ismade so liable to deflect that it can be easily mounted on theperipheral edge of the opening W, because the air bag 11 is yet to beexpanded, and thereby no tension line is formed.

Here, the first embodiment is exemplified by the construction in whichthe integrating joint 21 is formed at the back of the projecting sidejoint 20b for forming the expansion chamber 18. By omitting the rearside of the projecting side joint 20b at one side of the outer side wall13 or the inner side wall 12, however, the rear side of the projectingside joint 20b may be formed of one sheet of cloth material of the innerside wall 12 or the outer side wall 13. As in the air bag 461 shown inFIG. 27, alternatively, a band-shaped strap 110 made of a cloth materialhaving mounting holes 110a for inserting the bolts 38 therethrough maybe stitched to the projecting side joint 20b. In such a case, it ispossible to eliminate the joint means 10 such as the stitching thread10a for forming the integrating joint 21, one side wall 13 or 12 at theback of the projecting side joint 20b, and the joint means such as themounting side joint 20a at the back of the projecting side joint 20b.Thus, the air bag 461 can be folded more compactly.

An air bag 51 of a second embodiment, as shown in FIG. 28, is soconstructed as to be supported a center pillar (or B pillar), so thatwhen the air bag 51 is expanded, by locating the center pillar CP in theexpansion area at the time of expansion.

This air bag 51 is accommodated in a folded state to extend across thefront pillar (or A pillar) FP and the roof side rail RR, as shown inFIG. 29, and a front side fixed point 51A is jointed to the inflator 24under the front pillar FP. On the other hand, the air bag 51 is set atits rear fixed point 51B on the roof side rail RR near a quarter pillarQP (or C pillar).

Moreover, the air bag 51 is fixed at its oblique side 55 on thecompartment side of the front pillar FP by bolts 78, and at its upperside 54 on the compartment side of the roof side rail RR by the bolts78. In the upper side 54 and the oblique side 55, there are formed themounting holes for inserting the individual bolts 78 therethrough.

In the air bag 51, moreover, there are juxtaposed along the tension lineL--L four joints 62 (62F, 62S, 62T and 62B) for establishing tensions.As shown in FIG. 30, five expansions 58c, 58d, 58e, 58f and 58g arelongitudinally formed to cross the tension line L--L individually.

The individual joints 62F, 62S, 62T and 62B are arranged generally atthe vertically middle portions of the air bag 51 to form spaces 58a and58b over and under the vertically midde portions for passing theexpanding gas at the time of expansion.

On the other hand, the air bag 51 is manufactured to form the individualjoints 62 by folding back one cloth material at a lower side 56, bystitching the portions (i.e., the upper side 54, the oblique side 55 andthe rear side 57) excepting the lower side 56 with the stitching thread10a into a bag shape, and by stitching the predetermined portions of theinner side wall 12 and the outer side wall 13 with the stitching thread10a.

Moreover, the air bag 51 is so arranged that the expansion 58f at itsrear side overlaps the center pillar CP. In this expansion 58f, thespacing between the adjoining joints 62T and 62B is set larger than thatbetween the adjoining joints 62F and 62S or 62S and 62T in the remainingexpansions 58d and 58e so that the expansion 58f has a larger thicknessH1 than that H2 of the remaining expansions 58d and 58e.

On the other hand, the air bag 51 of the second embodiment isaccommodated in a folded state in a case 69, which is arranged over thefront pillar FP and the roof side rail RR. The air bag 51 is folded, asshown in FIGS. 31 and 34, such that its overlapping faces S aregenerally at a right angle with respect to a door glass inner face GI.

As shown in FIGS. 31 to 33, the case 69 is accommodated between a frontpillar inner panel 71a or a roof side inner panel 71d in a vehicle body71 and a garnish 73 or a roof interior member 75. The case 69 is made ofa synthetic resin such as polypropylene and is constructed to include anouter side wall 69a and an inner side wall 69e. This inner side wall 69eis composed of a flat portion 69f and a lid 69i having a U-shapedsection. A V-notch 69d is formed at the jointed portion between the lid69i and the outer side wall 69a. At the time of expansion of the air bag51, the V-notch 69d is broken so that the lid 69i is turned on the lidsown site, because the lid 69i is hinged to the flat portion 69f of theinside of the compartment to project the air bag 51.

At the outer side wall 69a and the flat portion 69f of the inner sidewall 69e, on the other hand, there are formed engaging pawls 69c and 69hwhich can engage with each other to hold the air bag 51 in the foldedstate. In the outer side wall 69a and the flat portion 69f of the innerside wall 69e, moreover, there are formed corresponding through holes69b and 69g so that the case 69 is fixed together with the air bag 51 onthe compartment side portions of the front pillar inner panel 71a andthe roof side inner panel 71d by means of the bolts 78 extending throughthe through holes 69b and 69g and nuts 79 fastened on the bolts 78.

Moreover, the air bag 51 is folded such that its folded portion isaccommodated in the lid 69i. The air bag 51 is so arranged in the case69 that its upper side 54 and oblique side 55 can be clamped between theouter side wall 69a and the flat portion 69f of the inner side wall 69e.The folded air bag 51 can be mounted together with the case 69 in thevehicle by bringing the engaging pawls 69c and 69h into engagement witheach other, and by fastening the bolts 78 and the nuts 79 to the frontpillar inner panel 71a and the roof side inner panel 71d through thethrough holes 69b and 69g and the air bag mounting holes in the upperside 54 and the oblique side 55.

Here, the garnish 73 and the roof interior member 75 are assembled withthe vehicle after the air bag 51 is mounted.

Moreover, reference numeral 71b in FIG. 31 designates a front pillarouter panel, and numeral 71c designates a front pillar reinforcement. InFIG. 33, moreover, reference numeral 71e designates a roof side member,numeral 71f a roof side rail outer reinforcement, and numeral 71g a roofpanel.

When the air bag 51 is to be inflated and expanded, it breaks theV-notch 69d of the case 69 to open the lid 69i. Then, the gap betweenthe garnish 73, as closed by a weather strip 74, and the front pillarinner panel 71a, and the gap between the roof interior member 75, asclosed by a weather strip 76, and the roof side inner panel 71d, areopened wide to allow the air bag 51 a large expansion.

At this time, the inflating gas is quickly fed from the inflator 24 intothe upper and lower spaces 58a and 58b in the peripheral edge of the airbag 51 and further to a plurality of expansions 58c, 58d, 58e, 58f and58g so that the air bag 51 is expanded within a short time period.

On the other hand, the expansions 58c, 58d, 58e, 58f and 58g, ascrossing the tension line L--L jointing the front side fixed point 51Aand the rear side fixed point 51B of the air bag 51, can be inflated toestablish a high tension reliably on the tension line L--L. Moreover,the longitudinally extending lower space 58b can also be expanded tomake the air bag 51 difficult to bend while retaining a high restrainingperformance on the passenger.

In the air bag 51 of the second embodiment, moreover, the front sidefixed point 51A is set near and under the front pillar FP, and the rearside fixed point 51B is set at the roof side rail RR near the quarterpillar QP. As a result, the air bag 51 can be expanded over theentireity of the longitudinal wide range along the compartment side torestrain the head 80a of a passenger 80 reliably, even with changes inthe longitudinal position of the seat FS, such as the seat of a driveror a navigator, and in the seated position of the passenger.

In the second embodiment, moreover, the front side fixed point 51A ofthe air bag 51 is set at the joint of the inflator 24 under the frontpillar FP. As compared with the case in which the front side fixed point51A is set at the compartment side such as the front pillar FP,therefore, the front side fixed point 51A of the air bag 51 can be setat a lower position to protect the head 80a of the passenger 80 over awider range.

In accordance with this point of view, a rear side fixed point 511B maybe set under the quarter pillar QP, as in the air bag 511 shown in FIG.36. In this modification, the air bag 511 can protect not only thepassenger 80 seated on the front seat for the driver or the navigator,but also the head 80a of the passenger 80 seated on a back seat BS.

In the air bag 51 of the second embodiment, on the other hand, theexpansion area covers the center pillar CP so that the air bag 51 issupported by the center pillar CP even if it is pushed to the outside ofthe vehicle by the head 80a of the passenger 80. As a result, the airbag 51 can become even more difficult to bend, in order that it can havea more enhanced performance in terms of restraining the passenger's head80a.

In the second embodiment, moreover, the thickness H1 of the expansion58f, as supported by the center pillar CP, of the air bag 51 beingexpanded is set larger than the thickness H2 of the remaining ordinaryexpansions 58d and 58e. As a result, the cushioning effect can beenhanced, even with an interference of the air bag 51 with the centerpillar CP, in order to better restrain the passenger's head 80a. Ascompared with the case in which the expansion 58f to be supported by thecenter pillar CP is made as thick as the remaining ordinary expansions58d and 58e, the cushioning effect can be retained even under a lowerinitial pressure in the air bag 51. As a result, it is possible toreduce the output of the inflator 24 and to simplify the sealing methodof the air bag 51, thereby resulting in a reduction of the size of aside air bag device M2.

In the second embodiment, on the other hand, in connection with theexpansion 58f supported by the center pillar CP, the gap between theadjoining joints 62T and 62B is made larger than the gaps between theadjoining joints 62F and 62S and 62S and 62T of the remaining ordinaryexpansions 58d and 58e. As a result, the expansion 58f to be supportedby the center pillar CP can be easily made thicker than the remainingordinary expansions 58d and 58e.

Moreover, the air bag 51 of the second embodiment is accommodated in thecase 69, and is fixed together with the case 69 onto the front pillarinner panel 71a and the roof side inner panel 71d so that the air bag 51can be prevented from collapsing by the case 69. With this case 69, theair bag 51 can be prevented, when assembled, from depending out ofposition, thereby improving its assembly characteristics. With the case69, moreover, the air bag 51 is not twisted, when assembled, so that theair bag 51 can be reliably accommodated with its overlapping faces Sbeing generally at a right angle with respect to the door glass innerface GI.

Moreover, this case 69 is equipped with the engaging pawls 69c and 69hfor engaging with each other to hold the air bag 51 in the folded stateso that the air bag 51 can be easily accommodated in the case 69 bybringing the engaging pawls 69c and 69h into and out of engagement. Itis quite natural that the engaging pawls 69c and 69h are disposed nearthe through holes 69b and 69g providing the mounting sides of the innerpanels 71a and 71d so that they impart no influence upon the expandingperformance of the air bag 51.

Here, a case 89 may be constructed, as shown in FIG. 34, to include anouter side wall 89a outside of the compartment and an inner side wall89f inside of the compartment. The outer side wall 89a may be comprisedof a flat wall 89b having a through hole 89c for admitting the bolt 78and a bottom 89d bent at a right angle from the front wall 89b. Theinner side wall 89f may be composed of a flat wall 89g having a throughhole 89h connected to the flat wall 89b for admitting the bolt 78, and alid 89i having an L-shaped section. Engaging pawls 89e and 89j may beformed to engage with the bottom 89d and the lid 89i to hold the air bag51 in the folded state. In this case 89, when the air bag 51 isinflated, the engaging pawls 89e and 89j are released from theirengagement, so that the bottom 89d is turned and opened on its portionjointed to the flat wall 89b, whereas the lid 89i is also turned andopened on its portion jointed to the flat wall 89g, thereby to projectthe air bag 51.

With the design of preventing the air bag 51 from being collapsed, onthe other hand, the air bag 51 may be wrapped with a synthetic resinfilm such as a polyethylene film 90 having a thickness that allows aneasy rupture at the time of expansion of the air bag 51, as shown inFIG. 35, before it is accommodated in the cases 69 and 89.

With this construction, it is possible to prevent the air bag 51 fromcollapsing, as well as a foreign substance from entering into the airbag 51 being folded. If the wrapping is performed under a vacuum state,the air bag 51 can be folded more compactly to make the followingcontributions. Specifically, by wrapping the front pillar FP can be madethinner to improve the front view, and the roof side rail RR can also bemade thinner to extend the compartment.

Here, the air bag can be mounted like the foregoing air bags 51 and 511on a four-door vehicle having front and rear seats, but can also beapplied to a two-door car having two seats, as shown in FIG. 37. In thismodification, the air bag 51 is constructed so as to wrap the centerpillar CP when expanded.

On the other hand, the first and second embodiments have been describedfor the air bags 11 and 51 which are arranged from the front pillar FPto the roof side rail RR in the compartment. In spite of thisdescription, however, the invention may be applied to an air bag to bearranged in such an inverted L-shaped portion of the peripheral edge ofthe opening W of the door as is extended from the quarter pillar QP atthe rear side of the vehicle or the center pillar CP to the roof siderail RR within the compartment. In this modification, the inflator 24and the gas inlet 19 are arranged under the quarter pillar QP or thecenter pillar CP.

Industrial Applicability

As has been described above, the air bag of a side air bag deviceaccording to the invention is useful for reducing the size and weight ofthe side air bag device.

What is claimed is:
 1. An air bag for a side air bag device adapted tobe mounted on the peripheral edge of a door opening inside of thecompartment of a vehicular body, comprising:an air bag having agenerally rectangular bag shape having a gas inlet for introducing aninflating gas so as to cover said door opening when inflated, and atensing joint partially jointing an inner side wall and an outer sidewall is arranged to form a tension line for establishing a tension froma lower side to an obliquely upper side of said door opening peripheraledge at the time of expansion, such that a plurality of said tensingjoints are juxtaposed along the direction of said tension line so as tocross said tension line, such that said individual tensing joints arearranged generally at vertical middle portions so as to form oneexpansion chamber having upper and lower spaces for said inflating gasto flow therethrough, and such that said individual tensing joints areshaped to have curved bulges bulging toward said gas inlet.
 2. An airbag for a side air bag device as set forth in claim 1, characterized inthat said individual tensing joints have recesses at the side opposed tosaid gas inlet so as to be recessed toward said gas inlet.
 3. An air bagfor a side air bag device as set forth in claims 1 or 2, characterizedin that a joint arranged at the peripheral edge for forming saidexpansion chamber and said individual joints for establishing saidtension are formed by stitching said inner side wall and said outer sidewall.
 4. An air bag for a side air bag device as set forth in claims 1or 2, characterized in that a joint arranged at the peripheral edge forforming said expansion chamber and said individual joints forestablishing said tension are formed by stitching said inner side walland said outer side wall together with a sheet material havingelasticity disposed between said inner side wall and said outer wall. 5.An air bag for a side air bag device as set forth in claim 3, whereinsaid individual tensing joints are formed by stitching said inner sidewall and said outer side wall into a closed loop.
 6. An air bag for aside air bag device as set forth in claim 1, such that a joint arrangedat the peripheral edge for forming said expansion chamber and saidindividual joints for establishing said tension are formed by adheringsaid inner side wall and said outer side wall.
 7. An air bag for a sideair bag device as set forth in claim 1, characterized in that a frontside fixed point is set under a front pillar, whereas a rear side fixedpoint is set in a roof side rail near a quarter pillar.
 8. An air bagfor a side air bag device as set forth in claim 1, characterized in thatsaid air bag is so arranged that its expansion area includes wheninflated, a portion of a center pillar so as to be supported by saidcenter pillar when inflated.
 9. An air bag for a side air bag device asset forth in claim 1, characterized in that a front side fixed point isset under a front pillar, whereas a rear side fixed point is set under aquarter pillar.
 10. An air bag for a side air bag device as set forth inclaim 1, characterized in that a front side fixed point is set under afront pillar.
 11. An air bag for a side air bag device as set forth inclaim 1, characterized in that a strap for jointing said inner side walland said outer side wall to each other is arranged between said jointsat the side of said gas inlet and a gas outlet.
 12. An air bag for aside air bag device as set forth in claim 11, characterized in that saidstrap is arranged to have a width direction generally at a right anglewith respect to the inflow direction of said expanding gas from said gasinlet.
 13. An air bag for a side air bag device adapted to be mounted onthe peripheral edge of a door opening inside of the compartment of avehicular body, comprising:an air bag having a generally rectangular bagshape having a gas inlet for introducing an inflating gas so as to coversaid door opening when inflated, and having a tensing joint partiallyjointing an inner side wall and an outer side wall is arranged to form atension line for establishing a tension at the time of expansion, suchthat a plurality of said tensing joints are juxtaposed along thedirection of said tension line so as to cross said tension line, suchthat said individual tension joints are arranged generally at verticalmiddle portions so as to form one expansion such that said air bag is soarranged that its expansion area includes, when inflated, a portion of acenter pillar so as to be supported by said center pillar when expanded,and such that said portion to be supported by the center pillar at thetime of inflation is expanded such that said portion is thicker than theremaining ordinary expansion thickness.
 14. An air bag for a side airbag device as set forth in claim 13, characterized in that the expansionto be supported by said center pillar at the time of expansion is formedsuch that a gap between the adjoining joints is set to be larger thanthat of the adjoining joints in the remaining ordinary expansionportions.
 15. A side air bag device for installation in a vehicularbody, comprising:an air bag having an inner wall and an outer walladapted to be mounted on a peripheral edge of a door opening on aninside of the vehicular body, and folded and accommodated along a roofside rail such that said air bag is capable of inflating to cover thedoor opening; wherein said air bag includes an upper side mounted onsaid roof side rail of said vehicular body and a lower side extending ina front and a rear of the air bag and arranged to face said upper sideand a free end of the air bag; wherein a plurality of joints joint theinner wall and the outer wall in a position between said upper side andsaid lower side and restrict expansion of said air bag, said pluralityof joints divide said upper side from said lower side; wherein an upperspace for an inflating gas to flow therethrough is defined in said upperside; and wherein the air bag is folded in a bellows shape with saidinner wall and said outer wall collapsed together and overlapping eachother such that folded overlapping faces are generally at a right anglewith respect to a door inside face of said vehicular body.
 16. An airbag for a side air bag device as set forth in claim 15, characterized inthat the expansion chamber of said air bag is manufactured by foldingone cloth material and by jointing the peripheral edges of said clothmaterial excepting the creases thereof such that the creases of thecloth material at the time of forming said expansion chamber arearranged at the portions which are to be folded into the belows shape atthe time of accommodation.
 17. A side air bag for a side air bag deviceas set forth in claim 15 or 17, a projecting side joint in theperipheral edge of the cloth material for forming the expansion chamberis arranged to be cross folded in an overlapping direction whenaccommodated in said side air bag device.
 18. An air bag for a side airbag device as set forth in claim 15, characterized:in that said air bagis formed, when expanded, into a parallelogram bag shape having twosides of an upper side having mounting members to be mounted on theperipheral edge of the opening inside of the compartment, and an obliqueside leading at an obtuse angle obliquely downward from said upper side;and in that said air bag is folded and accommodated to have creases inparallel with said upper side and to overlap said upper side at a rightangle.
 19. An air bag for a side air bag device as set forth in claim15, characterized in that said air bag is accommodated in a case to befastened together on said body.
 20. An air bag for a side air bag deviceas set forth in claim 15, characterized in that said air bag is wrapped,when accommodated, in a folded state.
 21. The side air bag device as setforth in claim 15, wherein said joints are severally and linearly formedso as to extend in an up and down direction of said airbag and in adirection extending from the front to the rear of the airbag, such thata tension is established in said air bag when the air bag expands. 22.The side air bag device as set forth in claim 15, wherein said air bagdefines a lower space for the expanding gas to flow therethrough, saidlower space being defined in said lower side of said air bag.
 23. A sideair bag device for installation in a vehicular body, comprising:an airbag having an inner wall and an outer wall adapted to be mounted on aperipheral edge of a door opening on an inside of the vehicular body,and folded and accommodated along a roof side rail such that said airbag is capable of expanding to cover the door opening; wherein said airbag includes an upper side mounted on said roof side rail of saidvehicular body and a lower side extending in a front and a rear of theair bag and arranged to face said upper side and a free end of the airbag; wherein a plurality of joints join the inner wall and the outerwall in a position between said upper side and said lower side andrestrict expansion of said air bag, said plurality of joints divide saidupper side from said lower side; wherein a lower space for an inflatinggas to flow therethrough is defined in said lower side; and wherein theair bag is folded in a bellows shape with said inner wall and said outerwall collapsed together and overlapping each other such that foldedoverlapping faces are generally at a right angle with respect to a doorinside face of said vehicular body.
 24. The side air bag device as setforth in claim 23, wherein said joints are severally and linearly formedso as to extend in an up and down direction of said airbag and in adirection extending from the front to the rear of the airbag, such thata tension is established in said air bag when the air bag expands.
 25. Aside air bag device for installation in a vehicular body, comprising:anair bag having an inner wall and an outer wall adapted to be mounted ona peripheral edge of a door opening on an inside of the vehicular body,and folded and accommodated along a roof side rail such that said airbag is capable of expanding to cover the door opening; wherein said airbag includes an upper side mounted on said roof side rail of saidvehicular body and a lower side extending in a front and a rear of theair bag and arranged to face said upper side and a free end of the airbag; wherein a plurality of joints join the inner wall and the outerwall in a position between said upper side and said lower side andrestrict expansion of said air bag, said plurality of joints divide saidupper side from said lower side; wherein an upper space for an inflatinggas to flow therethrough is defined in said upper side of said air bagand a lower space for said inflating gas to flow therethrough is definedin said lower side; and wherein the air bag is folded in a bellows shapewith said inner wall and said outer wall collapsed together andoverlapping each other such that folded overlapping faces are generallyat a right angle with respect to a door inside face.
 26. The side airbag device as set forth in claim 25, wherein said joints are severallyand linearly formed so as to extend in an up and down direction of saidairbag and in a direction extending from the front to the rear of theairbag, such that a tension is established in said air bag when the airbag expands.